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What is 400 Bad Request?

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New User

What is 400 Bad Request?

When I try to enter my user ID & password into certain sites, I get the message: Your browser sent a request that this server could not understand. - and 400 Bad Request appears on the tab. This seemed to have begun occurring around the time I disabled most of my plug-ins to troubleshoot another problem I was having. Enabling the plug-ins again did not help this new problem. I've just uninstalled ff, dumped my profile, reinstalled and still have the same problem! Any help out there?

12 REPLIES
Site Moderator

Re: What is 400 Bad Request?

Clear the cache and the cookies from sites that cause problems.

  • "Clear the Cache": Firefox > Preferences > Advanced > Network > Offline Storage (Cache): "Clear Now"
  • "Remove the Cookies" from sites causing problems: Firefox > Preferences > Privacy > Cookies: "Show Cookies"
New User

Re: What is 400 Bad Request?

Thanks for the reply, but neither of the suggestions worked. I feel a little better knowing a couple other people are experiencing the same problem and would be interested if clearing the cache and removing cookies worked for anyone else. Here's another message I get along the same lines when placing an item in cart on quill.com:

Your browser sent a request that this server could not understand. Reference #7.b4daf180.1287607830.0

New User

Re: What is 400 Bad Request?

I've been getting this error multiple times a day on just ONE of my sites (a traffic exchange). It only happens in FireFox...I can view the site in IE, Chrome and Safari. Hosting company says it's not on their end. This is extremely frustrating as my TE is a business and FireFox is used by the majority of my members....when they can't surf they go to another TE.

Site Moderator

Re: What is 400 Bad Request?

If clearing the cookies doesn't help then it is possible that the file cookies.sqlite that stores the cookies is corrupted.

Rename (or delete) cookies.sqlite and cookies.txt, if they exist, in the Profile Folder in case cookies.sqlite got corrupted.

New User

Re: What is 400 Bad Request?

None of these suggestions above worked for me. I just started getting these 400 errors the last couple of weeks. Everything works fine on IE. When I reload the page after a 400 error it redirects fine to the page, but that's kind of annoying to do that every time. I've cleared all the cookies, cache, etc. I disabled all Add-ons. I cleared all my temporary files on my computer and uninstalled Firefox and re-installed it. I even looked for the cookies.sqlite and cookies.txt and they are not there. Any other suggestions anyone?

Site Moderator

Re: What is 400 Bad Request?

See Help > Troubleshooting Information > Profile Directory: Open Containing Folder

New User

Re: What is 400 Bad Request?

I have no back/forward button and I'm NOT going to pay someone to help me fix it. I prefer Mozilla Firefox and have encouraged dozens to use it but there is NO support and again, I'm not going to pay for support. Internet Express, which I hate, does have back/forward button so what the heck is going on with Firefox? You make PLENTY of money selling ads etc so get it together if you want us to continue using your browser. Or we will leave.  :/

Site Moderator

Re: What is 400 Bad Request?

If the menu bar is hidden then press the F10 key or hold down the Alt key, that should make the menu bar appear.

Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible: "View > Toolbars"

  • If items are missing then open the Customize window via "View > Toolbars > Customize" or via "Firefox > Options > Toolbar Layout"
  • If a missing item is in the toolbar palette then drag it back from the Customize window on the toolbar
  • If you do not see an item on a toolbar and in the toolbar palette then click the "Restore Default Set" button to restore the default toolbar set up.

See also:

New User

Re: What is 400 Bad Request?

When will this bug be address. It appears from 3.5 to 7.0.1. If we test the links in safari, internet explorer, and opera all of the recent version and the links work.


So the question is when will this be address, if the browser recieves a 400 Bad Request then is should not cache the response, and attempt to resolve the link again when the user refreshes.

Not clear what is the problem.